1. Field of the Invention
The present invention relates to a solid-state image device detecting different color component signals by color filters disposed on a plurality of pixels.
2. Description of the Related Art
Heretofore, in a solid-state image device used in a single-plate camera, a technique of performing spatial color separation has been generally used in which color filters having three RGB colors are disposed above individual pixels of the solid-state image device. According to this method, by optionally adjusting the spectral characteristics of the color filters, superior color reproducibility can be achieved; however, absorption by the cooler filters, there has been a problem in that light incident on the solid-state image device may not be efficiently used in some cases.
In addition, since spatial color separation is performed, the pixels of the solid-state image device may not be efficiently used. For example, when the number of the G pixels is small, the resolution of brightness signal may be disadvantageously decreased, and when the number of the R and/or B pixels is small, a problem such as decrease in resolution of color signal or generation of color pseudo signal may arise in some cases.
As a method for solving the problems as described above, a solid-state image device using the difference in absorption of light wavelengths in a bulk of silicon has been proposed (see PCT Japanese Translation Patent Publication No. 2002-513145). According to the method described above, three well regions are formed in a substrate along the depth direction thereof in conformity with the difference in absorption of RGB colors so as to collect photons of the RGB light in the respective well regions, and potential difference therebetween is measured (hereinafter referred to as “three-well structure”).
The three-well structure as described above has the following advantages as compared to the method performing spatial color separation using color filters.
(1) Loss in light due to absorption by a color filter is not generated, and hence the utilization rate of light is improved.
(2) Since a G signal functioning as a primary component of the brightness signal can be obtained from each pixel, an image having superior resolution can be obtained.
(3) Since sampling positions of respective RGB colors do not coincide with each other, a pseudo signal is unlikely to be generated.